The present invention relates generally to gas turbine engines, and, more specifically, to compressor stators therein.
A turbofan gas turbine engine includes in serial flow communication a fan, low and high pressure compressors, combustor, and high and low pressure turbines. Air is pressurized in the compressors and mixed with fuel in the combustor for generating hot combustion gases which flow downstream through the turbines. The high pressure turbine powers the high pressure compressor through a shaft therebetween, and the low pressure turbine powers the fan and low pressure compressor through another shaft therebetween.
The typical compressor includes many rows or stages of alternating stator vanes and rotor blades which increase the pressure of air as it flows downstream therethrough. A significant design challenge is to efficiently pressurize the air with as few compressor stages as possible. However, compressor efficiency is only one of many operating parameters for the compressor including strength and durability thereof under vibratory and centrifugal loads, and performance of the compressor over the entire flight envelope of operation with suitable stall margin.
Aerodynamic efficiency of the compressor blades and vanes is determined by the specific aerodynamic profiles thereof, as well as by the outer and inner flowpath boundaries therefor. Typical compressor design is based on two-dimensional analysis of the flowpaths therethrough, and results in relatively uniform shape of the blades and vanes in cylindrical or conical outer flowpaths.
However, actual flow of the air being compressed through the stages is not uniform over the radial span of the blades and vanes since the outer and inner flowpaths provide substantial interaction with the axially moving airflow.
Accordingly, it is desired to provide an improved compressor stator for further increasing efficiency thereof due to improvements in vane-flowpath configuration.
A compressor stator includes an outer casing supporting a row of stator vanes extending radially inwardly therefrom. Each vane includes pressure and suction sides extending axially between leading and trailing edges and radially between a root and a tip. The root and tip are twisted relative to a pitch section disposed therebetween. Each vane tip is radially convex adjacent a leading edge for defining an axially concave outer flowpath in :the casing for reducing peak velocity of airflow for enhanced efficiency.